This application is related to Japanese Patent Applications No. 2001-57260 filed on Mar. 1, 2001, and No. 2001-208011 filed on Jul. 9, 2001, the contents of which are hereby incorporated by reference.
1. Field of the Invention
The present invention relates to an ejector cycle system having an ejector. The ejector sucks gas refrigerant evaporated at a lower pressure side, and increases a pressure of refrigerant to be sucked into a compressor by converting an expansion energy to a pressure energy.
2. Description of Related Art
In a conventional ejector cycle system described in JP-U-55-26273, refrigerant-flowing direction in each of an interior heat exchanger and an exterior heat exchanger during a cooling operation is opposite to that during a heating operation. In this case, if a dimension of a refrigerant passage in each of the interior heat exchanger and the exterior heat exchanger is set to be suitable for the cooling operation, it is difficult to be suitable for the heating operation. Accordingly, it is difficult to improve heat-exchanging performance in each of the interior heat exchanger and the exterior heat exchanger, for both the cooling operation and the heating operation.
On the other hand, in a conventional ejector cycle system disclosed in JP-Y-59-13571, an ejector for the cooling operation and an another ejector for the heating operation are provided, and one of both the ejectors is switched for each of the cooling and heating operations. In this case, since refrigerant is decompressed and expanded only by the any one ejector, the pressure of refrigerant to be sucked into a compressor is higher than that in a general refrigerant cycle where refrigerant is decompressed and expanded by a decompression device such as an expansion valve and a capillary tube. Thus, when the pressure of refrigerant discharged from a compressor in this ejector cycle system is identical to that in the general refrigerant cycle, the temperature of a high-pressure side refrigerant in this ejector cycle system becomes lower than that in the general refrigerant cycle. Accordingly, in the heating operation, heating performance cannot be sufficiently improved.
In view of the foregoing problems, it is an object of the present invention to provide an ejector cycle system which improves heat-exchanging performance in an exterior heat exchanger and in an interior heat exchanger.
It is an another object of the present invention to provide an ejector cycle system with cooling operation and heating operation, which sufficiently increases heating temperature in the heating operation.
According to a first aspect of the present invention, in an ejector cycle system with an ejector having a nozzle and a pressure-increasing portion, the flow direction of refrigerant, flowing through at least one of an exterior heat exchanger and an interior heat exchanger in a cooling operation where heat is radiated from a compartment to an outside, is identical to that in a heating operation where heat is radiated from the outside to the compartment. Accordingly, heat-exchanging performance can be effectively improved in at least one of the exterior and interior heat exchangers. Because the flow direction of refrigerant flowing through at least one of the exterior heat exchanger and the interior heat exchanger can be set identical in both the cooling operation and the heating operation, a special member such as a refrigerant distribution member (e.g., a throttle) can be disposed at a refrigerant inlet side in each of the exterior heat exchanger and the interior heat exchanger, for example. In this case, refrigerant-distribution performance in each of the exterior heat exchanger and the interior heat exchanger can be improved.
In the ejector cycle system of the present invention, first to fourth switching units are disposed, so that the flow direction of refrigerant flowing through each of the exterior heat exchanger and the interior heat exchanger can be set identical in both the cooling operation and the heating operation. The first switching unit is disposed to switch one of a case where refrigerant flows from the compressor toward the exterior heat exchanger and a case where refrigerant flows from the compressor toward the interior heat exchanger. The second switching unit is disposed to switch one of a case where liquid refrigerant flows from the gas-liquid separator toward the interior heat exchanger and a case where liquid refrigerant flows from the gas-liquid separator toward the exterior heat exchanger. The third switching unit is disposed to switch one of a case where refrigerant flows from the exterior heat exchanger into the nozzle of the ejector and a case where refrigerant flows from the interior heat exchanger into the nozzle of the ejector. The fourth switching unit is disposed to switch one of a case where refrigerant flows from the interior heat exchanger into the pressure-increasing portion of the ejector and a case where refrigerant flows from the exterior heat exchanger into the pressure-increasing portion of the ejector.
According to a second aspect of the present invention, in an ejector cycle system having the ejector, a decompression unit for decompressing refrigerant flowing from the interior heat exchanger is disposed. In addition, in the cooling operation for cooling the compartment, the high-pressure side refrigerant is decompressed by the ejector. On the other hand, in the heating operation for heating the compartment, the high-pressure side refrigerant is decompressed by the decompression unit. Accordingly, in the heating operation, the pressure of refrigerant to be sucked into a compressor can be made lower, and the temperature of refrigerant discharged from the compressor is increased. As a result, heating performance can be improved in the heating operation, while cooling performance is improved in the cooling operation.